1. Field of the Invention
The present invention relates to electro-mechanical displacement transducers and more particularly to frictionless electro-mechanical displacement transducers for long stroke measurements such as linear variable differential transformers and electro-capacitance transducers.
2. Description of the Prior Art
Two general types of transducers for detecting a mechanical displacement or stroke in the form of electrical signals are well known. A first known type of electro-mechanical transducer is a linear variable differential transformer. The linear variable differential transformers have excellent accuracy and resolution. However, their measurable strokes or displacements are restricted to a certain amount due to their principle of operation.
A second known type of electro-mechanical transducer is an electro-capacitance transducer. In these transducers measurable strokes beyond 2000 mm are now available, but their resolution of detecting mechanical displacement or stroke is only 0.25% or so. Both types of electro-mechanical displacement transducers mentioned above work usually successfully, but in a long stroke or displacement measurement we have not been satisfied with their performances from the viewpoint of accuracy and resolution.
An object of the invention is to provide an electro-mechanical displacement transducer apparatus with a new principle of operation, and having a probe which is easier to fabricate and more versatile than known previous devices.
A further object is to provide such an apparatus in which mechanical displacement is detected in the form of electric propagation delay of a voltage waveform on the probe, which delay may be time-coded by a clock oscillator.
A further object is to provide such an apparatus which eliminates the above-mentioned problems of the known types of electro-mechanical displacement transducers.